Study On Key Problems Of Post-processing In Five Axis Cnc Machining

Post-processing technology is one of the key technologies in 5-axis linkage CNC machining.It is the center and bridge connecting CAD/CAM system with CNC machining.The excellence of post processing will directly affect the surface quality,machining efficiency and stable operation in each axis of the machine tool.For complex surfaces,such as the blade,the impeller and other parts,the high-speed,high-precision,and high-efficiency processing technology requirements for 5-axis CNC machine tools highlight the importance of post-processing technology.For the key problem of 5-axis linkage NC machining post-processing,this paper takes the BV100 5-axis double turntable AC CNC machining center as the research object,and develops the special post-processing software for the corresponding technical requirements.The main research contents of the paper are as follows:(1)Based on the characteristics of 5-axis linkage NC machine tool's own structure kinematic chain,the 5-axis linkage CNC machine tool processing kinematic chain relationship is analyzed,and the machine tool kinematics coordinate system is established,so as to solve the movement of each axis of the machine tool.(2)For the nonlinear error problem,the principle of error caused by the linear interpolation of 5-axis linkage rotary axis is depthly analyzed.The mathematical model of nonlinear error is established and the linear interpolation formula is pushed;the RTCP algorithm and tool axis vector are proposed to reduce the nonlinear error.The MATLAB simulation analysis and verification algorithm can effectively reduce the nonlinear error.The influence of the tool parameters on the nonlinear error is also studied in detail,and the corresponding control measures are proposed.(3)Aiming at 5-axis linkage,due to the participation of the rotary axis,the surface quality of the part is reduced and the machining efficiency is caused by the inconsistency between the tool point and the tool center point speed,and a constant surface feed speed control method is proposed.Through MATLAB simulation analysis to verify the correctness of the algorithm and shorten the processing time by 32.46%.(4)In order to reduce the precision of the parts caused by tool wear in five axis NC machining,the 3D error compensation strategy is proposed.Firstly,the compensation principle of space tool radius is analyzed.To determine the relationship between the direction vector of the space tool radius compensationwith the cutter contact surface normal vector;Secondly,the mathematical model of tool machining is established,to calculate the compensation vector;Finally based on MATLAB simulation analysis to verify that the algorithm can achieve the function of tool radius compensation.(5)Based on post-processing technology,according to the movement relationship and related technical parameters of each axis of BV100,using JAVA high-level language to develop special post-processing software with multiple function modules;Based on VERICUT simulation software,the simulation model of machine tool was established,and the simulation processing environment was built;The VERICUT simulation software was used to simulate the NC code of a blade part,and a blade cutting experiment was performed on the machine tool,verifying the correctness and practicability of the post-processing software.